The present invention relates generally to the pneumatic supply systems of a nuclear powerplant; and more particularly to a system for providing an emergency pneumatic supply to air operated devices used in the nuclear plant.
FIG. 1 is a schematic, illustrating an environment within which an embodiment of the present invention operates. Specifically, FIG. 1 illustrates a non-limiting example of a known pneumatic supply system used to operate an air-operated valve 75 located inside a containment building 130 (hereinafter “inside containment”) of the nuclear power plant 10. As illustrated in FIG. 1, pneumatic fluid for operation of an air-operated valve 75 may be provided from either a pressurized tank 15, which stores for example, but not limiting of, nitrogen; or from an air compressor 20. A pressure regulator 25 typically controls the operating pressure of the pneumatic fluid. A valve 30 adjacent the containment wall 133 may be manually closed to prevent a loss of pneumatic pressure in the system when either: the pressurized tank 15, or the air compressor 20 is not available.
A pneumatic system pipeline passes through a penetration in a containment wall 133. A check valve 35 generally serves to reduce the chance of potentially radioactive gases from inside containment 130 from escaping through the containment wall 133. The downstream pneumatic pipeline 45 may be a relatively long length of pipe that may be accidentally damaged inside containment 130. A restricting flow orifice 40 serves to limit the flow of the pneumatic fluid inside containment 130, if the pipeline 45 ruptures downstream of the orifice 40. Check valve 50 is provided just upstream of accumulator 55, and serves to prevent a loss of pressure from the accumulator 55 if the long pipeline 45 ruptures.
The accumulator 55 is generally sized to ensure that sufficient pneumatic fluid is supplied for operating the valve 75. The accumulator 55 is considerably larger than is required for operation of the valve 75, allowing for loss from pneumatic fluid leakage through the check valve 50, the relief valve 60, or the solenoid valve 65, if the pneumatic system malfunctions. A relief valve 60 generally serves to protect the system from an over-pressurization if the pressure regulator 25 does not adequately control the pressure; or from over-pressurization due to higher than normal temperatures near the accumulator 55.
Operationally, when the solenoid valve 65 is opened, pneumatic fluid is routed to the air-operator 70 to move the valve 75. The air-operator 70 may be of any type including, but not limiting to, a diaphragm, a bellows, a piston, or the like. The valve 75 may be of any type, including, but not limiting to, a gate valve, a globe valve, a ball valve, an air damper, or the like. The valve 75 may be designed to open or close after an accident within the nuclear powerplant 10.
There are a few possible problems with the currently known pneumatic supply systems. The current systems require substantial piping and isolation devices. Installation, maintenance, and operation of these systems generally require accumulators, containment penetrations, and excessive valving configurations to guard against leaks between the areas inside containment 130 and outside containment 135. These systems also require longer installation and maintenance time; which can possibly expose operators to longer periods of radioactivity.
Based on the above discussion, an operator of a nuclear powerplant 10 may desire a system that provides an emergency pneumatic source to a component, such as, but not limiting of, a valve 75, within an area inside containment 130. The system should be locatable inside containment 130 and remotely operable. The system should require fewer components than currently known systems.